Effect of insufflation gas and intraabdominal pressure on portal venous flow during pneumoperitoneum in the rat

BACKGROUND: Carbon dioxide, the primary gas used to establish a pneumoperitoneum, causes numerous systemic effects related to cardiovascular function and acid-base balance. Therefore, the use of other gases, such as helium, has been proposed. Furthermore, the pneumoperitoneum itself, with the concomitant elevation of intraabdominal pressure, causes local and systemic effects that have been only partly elucidated. Portal blood flow, which plays an important role in hepatic function and cell-conveyed immune response, is one of the affected parameters. METHODS: An established animal model (rat) of laparoscopic surgery was extended by implanting a periportal flow probe. Hemodynamics in the portal vein were then measured by transit-time ultrasonic flowmetry during increasing intraabdominal pressure (2-12 mmHg) caused by gas insufflation (carbon dioxide vs helium). RESULTS: The installation of the pneumoperitoneum with increasing intraperitoneal pressure led to a significant linear decrease in portal venous flow for both carbon dioxide and helium. At higher pressure levels (8-12 mmHg), portal blood flow was significantly lower (1.5-2.5-fold) during carbon dioxide pneumoperitoneum. An intraabdominal pressure of 8 mmHg caused a decrease to 38.2% of the initial flow (helium, 59.7%); whereas at 12 mmHg, portal flow was decreased to 16% (helium, 40.5%). CONCLUSION: Elevated intraabdominal pressure generated by the pneumoperitoneum results in a reduction of portal venous flow. This effect is significantly stronger during carbon dioxide insufflation. Portal flow reduction may compromise hepatic function and cell-conveyed immune response during laparoscopic surgery.     

The impact of gas laparoscopy on abdominal plasminogen activator activity

Background: The impairment of intestinal perfusion following induction of a pneumoperitoneum may lead to a reduction of peritoneal tissue plasminogen activator (tPA) activity and a concomitant increased risk of adhesion formation. Methods: Pigs were laparotomized to take peritoneal biposy specimens from the cecum, the ileum, and the abdominal wall. A 15 mmHg pneumoperitoneum was established for 3 h by the insufflation of carbon dioxide (group 2, n = 6) or helium (group 3, n = 6). Group 1 (n = 7) received no gas insufflation. After a 2-h recovery period, additional tissue samples were harvested. Specific tPA activity was then determined in the tissue extracts. Results: During surgery, specific tPA activity decreased in all the samples. As compared with the control group (100%), this reduction was strongly aggravated in the cecum (-67.6%, p < 0.05) and the ileum (-70.8%) of the CO2 group but only slightly aggravated in the helium group. The parietal peritoneum was not specifically affected by gas insufflation. Conclusion: The use of a pneumoperitoneum with carbon dioxide significantly affects peritoneal tPA activity and thus may represent a stimulus for adhesion formation. apd: 13 March 2001     

Microsphere intestinal blood flow analysis during pneumoperitoneum using carbon dioxide and helium

Background Pneumoperitoneum has been associated with a decreased flow in the superior mesenteric artery and portal venous system. Intestinal blood flow was studied during a 2-h pneumoperitoneum with carbon dioxide (CO₂) or helium in a porcine model using colored microspheres.Methods For this study, 12 pigs were divided into two groups (6 CO₂ and 6 helium). Different colored microspheres were injected directly into the left ventricle before, 40, 80, and 120 min after insufflation with either gas at a pressure of 15 mmHg. Microsphere concentration was measured in the mucosa and muscularis/serosa layers of the jejunum, cecum, and sigmoid colon to calculate blood flow.Results Intestinal perfusion initially increases with insufflation and returns to near baseline levels during pneumoperitoneum of 2 h. The effect of helium on tissue perfusion is similar to that of carbon dioxide.Conclusions Intestinal perfusion does not change significantly during prolonged pneumoperitoneum at a pressure of 15 mmHg with CO₂ or helium.Podium presentation at the 2004 meeting of the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES), Denver, Colorado, USA, 31 March-3 April, 2004     

Effect of carbon dioxide pneumoperitoneum on tissue blood flow in the peritoneum,rectus abdominis,and diaphragm muscles

Background: Changes in local blood flow may play a role in the pathogenesis of port-site metastasis. This study aimed to investigate the effect of pneumoperitoneum induced by carbon dioxide (CO₂) on the blood flow in the peritoneum and abdominal wall muscle layers, which are target structures for this phenomenon. Methods: The study was performed on domestic farm swine of both genders weighing 20 to 25 kg. Intraabdominal pressures (IAP) of 0, 5, and 10 mmHg were produced by either CO₂ (n = 9) or helium (He) (n = 6) insufflations. The colored microsphere technique was used to measure blood flow distributions in the parietal peritoneum, rectus abdominis, and diaphragm muscles. Results: Insufflation of CO₂ was associated with a threefold increase in blood flow of the parietal peritoneum at both 5 and 10 mmHg IAP (p < 0.001 for both pressure levels). In contrast, insufflation of He caused a significant decrease in blood flow in the parietal peritoneum at both 5 and 10 mmHg (p < 0.05). In the rectus abdominis and diaphragm muscles, blood flow remained unchanged after insufflation of CO₂ at both 5 and 10 mmHg IAP. However, after insufflation of He, there was a substantial decrease in blood flow both in the rectus abdominis and diaphragm muscles at both 5 mmHg (p < 0.01 and p < 0.05, respectively) and 10mmHg (p < 0.001 and p < 0.01, respectively). Conclusions: Despite high intraabdominal pressure, tissues surrounding the abdominal cavity, particularly the peritoneum, respond to insufflation of CO₂ with increased blood flow, which may favor the growth of tumor cells.     

Effects of carbon dioxide vs helium pneumoperitoneum on hepatic blood flow

Background: Elevated intraabdominal pressure due to gas insufflation for laparoscopic surgery may result in regional blood flow changes. Impairments of hepatic, splanchnic, and renal blood flow during peritoneal insufflation have been reported. Therefore we set out to investigate the effects of peritoneal insufflation with helium (He) and carbon dioxide (CO₂) on hepatic blood flow in a porcine model. Methods: Twelve pigs were anesthetized and mechanically ventilated with a fixed tidal volume after the stabilization period. Peritoneal cavity was insufflated with CO₂ (n= 6) or He (n= 6) to a maximum intraabdominal pressure of 15 mmHg. Hemodynamic parameters, gas exchange, and oxygen content were studied at baseline, 90 mm and 150 min after pneumoperitoneum, and 30 min after desufflation. Determination of hepatic blood flow with indocyanine green was made at all measured points by a one-compartment method using hepatic vein catheterization. Results: A similar decrease in cardiac output was observed during insufflation with both gases. Hepatic vein oxygen content decreased with respect to the baseline during He pneumoperitoneum (p < 0.05), but it did not change during CO₂ insufflation. Hepatic blood flow was significantly reduced in both the He and CO₂ pneumoperitoneums at 90 min following insufflation (63% and 24% decrease with respect to the baseline; p < 0.001 and p < 0.05, respectively) being this decrease marker in the He group (p= 0.02). Conclusions: These findings suggest that helium intraperitoneal insufflation results in a greater impairment on hepatic blood flow than CO₂ insufflation. Received: 27 March 1996/Accepted: 19 January 1997     

Intraabdominal Carbon Dioxide Insufflation in the Pregnant Ewe: Uterine Blood Flow, Intraamniotic Pressure, and Cardiopulmonary Effects

Background: Laparoscopic surgical procedures are being performed in pregnant women with increasing frequency. Maternal-fetal physiologic changes occurring during intraabdominal carbon dioxide insufflation are poorly understood, and maternal-fetal safety is of concern during carbon dioxide pneumoperitoneum. A previous pilot study using end-tidal carbon dioxide-guided ventilation resulted in maternal and fetal acidosis and tachycardia during carbon dioxide pneumoperitoneum. Using serial arterial PCO2 to guide ventilation, this study was designed to evaluate maternal-fetal cardiopulmonary status, uterine blood flow, and the intraamniotic pressure effects of intraabdominal carbon dioxide insufflation in singleton pregnant ewes between 120 and 135 days of gestation.

Methods: In a prospective randomized cross-over study, nine ewes were to receive either abdominal insufflation with carbon dioxide to an intraabdominal pressure of 15 mmHg (n = 9; insufflation group) or receive no insufflation (n = 9; control group). Anesthesia was induced with thiopental and maintained with end-tidal halothane (1 to 1.5 minimum alveolar concentration/100% oxygen). Mechanical ventilation was guided by serial maternal arterial blood gas analysis to maintain PaCO2 between 35 and 40 mmHg. Data from insufflated animals were collected during insufflation (60 min) and after desufflation (30 min). Control group data were collected and matched to similar time intervals for 90 min. Ewes were allowed to recover, and after a rest period (48 h) they were entered in the cross-over study.

Results: During insufflation there was a significant increase (P <0.05) in maternal PaCO2 to end-tidal carbon dioxide gradient and minute ventilation, with concomitant decreases in maternal end-tidal carbon dioxide and PaO2. Intraamniotic pressure increased significantly during insufflation. No significant changes were observed in maternal hemodynamic variables, fetal variables, or in uterine blood flow during the study. There were no fetal deaths or preterm labor in any of the animals during the experiment.     

Effects of peritoneal insufflation on hepatic and renal blood flow

The effects of peritoneal insufflation with carbon dioxide on hepatic and renal blood flow have not been reported hitherto. We evaluated these effects in a porcine model of abdominal laparoscopic surgery. Seven anesthetized pigs underwent peritoneal insufflation in a step-wise manner to create intraabdominal pressures of 6, 12, 18 and 24 mmHg, and changes in the arterial and venous pressure, arterial blood gases, and hepatic and renal blood flow were monitored. Both the hepatic and renal blood flow decreased as the intraabdominal pressure increased. Therefore, in order to carry out laparoscopic abdominal surgery safely in patients with hepatic or renal impairment, low intraabdominal pressures or noninsufflating techniques are recommended.     

Effects of Intraabdominanlly Insufflated Carbon Dioxide and Elevated Intraabdominal Pressure on Splanchnic Circulation: An Experimental Study in Pigs

Background: Intraabdominally insufflated carbon dioxide (CO2) during laparoscopy may have a specific effect on splanchnic circulation that may be unrelated to the effects of increased intraabdominal pressure alone. Therefore, the influences of insufflation with CO2 versus air on splanchnic circulation were compared.

Methods: Pigs were chronically instrumented for continuous recording of mesenteric artery, portal venous, inferior vena cava, and pulmonary arterial blood flow and portal venous pressure. After induction of anesthesia, CO2 or air was insufflated in 14 and 10 pigs, respectively. With the pigs in the supine position, intraabdominal pressure was increased in steps of 4 mmHg up to 24 mmHg by graded gas insufflation.

Results: During air insufflation, mesenteric artery vascular resistance was unchanged, whereas mesenteric arterial blood flow decreased with increasing intraabdominal pressure. Shortly after CO3 insufflation to an intraabdominal pressure of 4 mmHg, mean arterial pressure, mesenteric arterial blood flow, and mesenteric arterial vascular resistance were increased by 21%, 12% and 9%, respectively. Subsequently, with the onset of CO2 resorption in the third minute, mean arterial pressure declined to baseline values and mesenteric arterial vascular resistance declined to 85% of baseline values, whereas mesenteric arterial blood flow continued to increase to a maximum of 24% higher than baseline values. At steady-state conditions during CO2 insufflation, mesenteric arterial blood flow was increased up to an intraabdominal pressure 相似文献   

Influence of acute hemorrhage and pneumoperitoneum on hemodynamic and respiratory parameters

Background: We examined the questions of whether resuscitated (compensated) acute hemorrhage enhances the negative effects of carbopneumoperitoneum on hemodynamic and respiratory parameters and whether pneumoperitoneum with helium has any advantages under these circumstances. Our investigation focused on the influence of acute hemorrhage with different gases on the cardiovascular and respiratory system as well as on hepatic and renal blood flow in a porcine model. Methods: Cardiac and hemodynamic function were monitored via implantation of catheters in pulmonary artery, femoral vein, and artery. Renal and hepatic blood flow were recorded using a transonic volume flow meter placed at the renal and hepatic artery and portal vein. Twelve animals were randomly assigned to one insufflation gas (carbon dioxide [CO₂] or helium [He]). Following baseline recordings, acute hemorrhage (20 ml/kg) was induced by continuous bleeding over 30 min. Animals then received a colloidal solution (20 ml/kg 6% hydroxyethylstarch solution) over 30 min. Pneumoperitoneum of 12 mmHg was established, and all parameters were measured after 30 min of adaptation. The major endpoints of the study were cardiac output (CO), arterial pressure (MAP), systemic vascular resistance (SVR), and central venous pressure (CVP), as well as blood flow in hepatic and renal artery and portal vein. Results: While CO and hemodynamic parameter as well as hepatic and renal blood flow were markedly reduced after hemorrhage, they returned nearly to their previous levels after resuscitation. Pneumoperitoneum with 12 mmHg did not further depress the cardiovascular system or reduce hepatic and renal blood flow. Pneumoperitoneum did not alter hepatic or renal blood flow. Pneumoperitoneum with helium did not substantially change the reaction of the cardiovascular system after resuscitated hemorrhage. Conclusions: If hemorrhage is compensated by proper resuscitation and hypovolemia is avoided, laparoscopic surgery with pneumoperitoneum of 12 mmHg appears to be not harmful. Using helium as the insufflating gas had no clear advantage over the carbon dioxide model. Received: 30 July 1997/Accepted: 24 October 1997     

The impact of carbon dioxide and helium insufflation on experimental liver metastases,macrophages, and cell adhesion molecules

Background: Laparoscopic insufflation, proposed to reduce hepatic perfusion, may enhance hepatic tumor spread. It is unknown whether intraabdominal pressure or the gas itself influences hepatic tumor growth. In contrast to carbon dioxide, the alternative gas helium is believed to reduce malignant cell growth. Methods: For this study, 36 WAG/Rij rats were randomized in two experimental groups. The animals were laparoscopically insufflated with carbon dioxide (n = 19) or helium gas (n = 17). Liver metastases were induced by laparoscopic injection of 50,000 CC531 cells into the portal vein. Macroscopic and microscopic analyses of CC531 tumor cell growth, macrophages, and CD44v5, v6 were performed. Data were analyzed by Kruskal-Wallis, Dunn, and Holm tests. Results: No significant differences in macroscopic and microscopic analyses were found between carbon dioxide and helium gas insufflations (p > 0.05). Conclusions: Recent studies have shown that insufflation with carbon dioxide may result in increased hepatic tumor growth. The current study comparing carbon dioxide and helium insufflations could show for the first time either oncologic nor immunologic differences in relation to the liver between two different gases. In conclusion, elevated intraabdominal pressure during gas insufflation is responsible for hepatic disadvantages during pneumoperitoneum, not carbon dioxide gas itself.     

Morphology of the murine peritoneum after pneumoperitoneum vs laparotomy

BACKGROUND: Although there have been studies of the effects of pneumoperitoneum on the peritoneal cavity, we still do not know whether the morphologic changes to the peritoneum are different for pneumoperitoneum vs laparotomy. Using scanning electron microscopy, we examined the murine peritoneum after pneumoperitoneum vs laparotomy and compared the changes. METHODS: Forty-five mice were anesthetized with diethyl ether and divided into seven groups. Pneumoperitoneum was established at 5 mmHg for 30 min with carbon dioxide (CO(2)) (n = 9), helium (n = 9), and air (n = 9). One group underwent laparotomy for 30 min (n = 9), and a control group underwent anesthesia only (n = 3). CO(2) pneumoperitoneum was further established at 10 mmHg for 30 min (n = 3) and at 5 mmHg for 60 min (n = 3). After the procedures, the peritoneum was resected from the mesenterium of the small intestine in each animal and examined by scanning electron microscope for morphologic changes of the mesothelial cells. RESULTS: Bulging up of the mesothelial cells was evident immediately after pneumoperitoneum, whereas detachment of the mesothelial cells was present immediately after laparotomy. Bulging up of the mesothelial cells was reduced at 24 h after CO(2) pneumoperitoneum and fully resolved at 72 h in all pneumoperitoneum groups, whereas the mesothelial cells remained detached at 72 h in the laparotomy group. Intercellular clefts were found immediately after helium pneumoperitoneum and were present at 24 h and 72 h after helium pneumoperitoneum, but they were not seen after air pneumoperitoneum and were only evident after CO(2) pneumoperitoneum at 10 mmHg. Depression of the mesothelial cell surface was observed when pneumoperitoneum lasted 60 min. CONCLUSION: Morphologic peritoneal alterations after pneumoperitoneum differed from those after laparotomy and were influenced by the type of gas, amount of pressure, and duration of insufflation. These peritoneal changes after pneumoperitoneum may be associated with a specific intraperitoneal tumor spread after laparoscopic cancer surgery.     

Are there changes in leg vascular resistance during laparoscopic cholecystectomy with CO2 pneumoperitoneum?

BACKGROUND: The prompt haemodynamic response to carbon dioxide insufflation during laparoscopic cholecystectomy suggests involvement of the sympathetic system. The aim of the present study was to examine if a change in vascular resistance in leg skeletal muscle could be an important mechanism behind the increased afterload. Furthermore, the arterio-venous differences of the catecholamines were measured in the leg before and during insufflation of carbon dioxide into the peritoneal cavity. METHODS: Ten patients (ASA I) scheduled for laparoscopic cholecystectomy were included. After induction of anaesthesia, catheters were introduced percutaneously into the radial artery, the femoral vein and the cubital vein for pressure monitoring and blood sampling. The arterial blood flow in the legs was measured by mercury-in-Silastic strain gauge venous occlusion plethysmography. Vascular resistance in the right leg (LVR) was calculated from the formula: (MAP-FVP)/calf blood flow. Measurements were made before and 5 min after insufflation of pneumoperitoneum. RESULTS: Induction of pneumoperitoneum increased the heart rate (P < 0.05) and also increased mean arterial pressure and femoral vein pressure as well as the calculated leg vascular resistance (P < 0.01). Calf blood flow did not change significantly in either leg. Both arterial and venous noradrenaline concentrations were higher after insufflation (P < 0.01). CONCLUSION: In patients without heart or lung disease, pneumoperitoneum at an intra-abdominal pressure level of 11-13 mmHg increased the peripheral vascular resistance in the leg while the arterial blood flow in the leg was unaffected. Catecholamine levels increased, but were still low. Therefore, we suggest that the increase in peripheral vascular resistance is caused by increased myogenic activity in the resistance vessels secondary to increased arterial and transmural pressure rather than by increased neurogenic sympathetic activity.     

Impact of carbon dioxide and helium insufflation on cardiorespiratory function during prolonged pneumoperitoneum in an experimental rat model

BACKGROUND: Experimental studies on laparoscopic surgery are often performed in rats. However, the hemodynamic and respiratory responses related to the pneumoperitoneum have not been studied extensively in rats. Therefore, the aim of this study was to investigate in spontaneously breathing rats the effects of CO2 and helium, insufflation pressure, and duration of pneumoperitoneum on blood pressure, arterial pH, pCO2, pO2, HCO3-, base excess, and respiratory rate. METHODS: Five groups of 9 Brown Norway rats were anesthetized and underwent CO2 insufflation (6 or 12 mmHg), helium insufflation (6 or 12 mmHg), or abdominal wall lifting (gasless control) for 120 min. Blood pressure was monitored by an indwelling carotid artery catheter. Baseline measurements of mean arterial pressure (MAP), respiratory rate, arterial blood pH, pCO2, pO2, HCO3-, and base excess were recorded. Blood gases were analyzed at 5, 30, 60, 90, and 120 min during pneumoperitoneum, and MAP and respiratory rate were recorded at 5 and 15 min and at 15-min intervals thereafter for 2 h. RESULTS: CO2 insufflation (at both 6 and 12 mmHg) caused a significant decrease in blood pH and increase in arterial pCO2. Respiratory compensation was evident since pCO2 returned to preinsufflation levels during CO2 insufflation at 12 mmHg. There was no significant change in blood pH and pCO2 in rats undergoing either helium insufflation or gasless procedures. Neither insufflation pressure nor the type of insufflation gas had a significant effect on MAP over time. CONCLUSION: The cardiorespiratory changes during prolonged pneumoperitoneum in spontaneously breathing rats are similar to those seen in clinical practice. Therefore, studies conducted in this animal model can provide valuable physiological data relevant to the study of laparoscopic surgery.     

Endoscopic endocrine neck surgery with carbon dioxide insufflation: the effect on intracranial pressure in a large animal model

BACKGROUND: Endoscopic endocrine neck surgery requires insufflation with carbon dioxide (CO(2)) at 10 to 15 mm Hg, which may decrease the cerebral venous return and increase intracranial pressure. This study evaluated the effect of CO(2) neck insufflation on intracranial pressure (ICP) and hemodynamic parameters. METHODS: Fifteen pigs underwent endoscopic thyroid dissection. Insufflation was performed with CO(2) at 0 (sham), 10, 15, and 20 mm Hg and with helium at 20 mm Hg with 3 pigs in each group. ICP, mean arterial pressure, central venous pressure (CVP), cardiac output, and blood gas were measured at baseline, 30, 60, and 120 minutes. RESULTS: There were no differences in mean ICP between the sham group and CO(2) insufflation at 10 mm Hg. Mean ICP increased significantly with CO(2) at 15 and 20 mm Hg and with helium at 20 mm Hg. A significant increase in CVP occurred in pigs operated with CO(2) at 20 mm Hg. We observed jugular vein collapse under all insufflation pressures; however, pigs operated at 10 mm Hg were able to maintain an intermittent blood flow. CONCLUSIONS: A severe increase in ICP occurs with insufflation pressures higher than 15 mm Hg, possibly as a result of decreased cervical venous blood flow. Carbon dioxide insufflation up to 10 mm Hg does not alter ICP and is recommended for clinical application in endoscopic neck surgery.     

Effectors of hypercarbia during experimental pneumoperitoneum.

Hypercarbia occurs during laparoscopy with carbon dioxide (CO2) insufflation. This may be due to increased ventilatory dead space after expansion of the peritoneal cavity with impairment of diaphragmatic excursion, or to increased absorption of CO2 from the peritoneum. To separate these effects, the authors examined the consequences of different insufflating gases and of diminished tissue perfusion on hypercarbia and dead space during pneumoperitoneum. Helium was chosen as an alternate insufflating gas because it is both inert and minimally absorbed. Eight swine (18 to 20 kg) were anesthetized, paralyzed, and mechanically ventilated at constant minute volume. Pneumoperitoneum with helium was maintained at 15 mm Hg for 45 minutes. After desufflation and stabilization for 1 hour, pneumoperitoneum was repeated with CO2. The sequence was again repeated after hemorrhagic shock to constant mean arterial pressure of 50 mm Hg. Data was analyzed by analysis of variance; significance levels are P < 0.01 unless otherwise listed. Arterial PCO2 increased significantly with CO2 insufflation within 15 minutes in normotensive animals and within 30 minutes during hypotension. Arterial pH decrease with CO2 pneumoperitoneum was significant in both groups at 30 minutes. Mixed venous PCO2 also increased with CO2 pneumoperitoneum within 30 minutes. Hypotension did not alter these changes. No significant changes were seen with helium pneumoperitoneum. Neither helium nor CO2 pneumoperitoneum significantly altered dead space. The authors make the following conclusions: 1) Absorption of CO2 from the abdomen during CO2 pneumoperitoneum produces respiratory acidosis, which is not seen with helium insufflation; 2) Pneumoperitoneum does not significantly increase dead space with either gas; 3) Transperitoneal absorption of CO2 is only partly related to perfusion because significant hypercarbia occurs during hemorrhagic shock.     

Peritoneal pH during laparoscopy is dependent on ambient gas environment: helium and nitrous oxide do not cause peritoneal acidosis

Background Little is know about the effects of different insufflation gases on peritoneal pH during laparoscopy. However, these changes may influence the intracellular signalling system, resulting in altered cell growth or adhesiveness. The aim of this study was to determine the effects of carbon dioxide (CO₂), nitrous oxide (N₂O), and helium (He) on parietal and visceral peritoneal pH. The effect of different intraabdominal pressures on parietal and visceral peritoneal pH was also examined.Methods We conducted both an ambient gas study and a pressure study. For the ambient gas study, 20 pigs were divided into the following four groups: (a) CO₂, (b) He, (c) N₂O, and (d) abdominal wall lift (Lift) laparoscopy. Parietal and visceral peritoneal pH were measured at 15 min intervals for 180 min. For the pressure study, 15 pigs were divided into the following three groups: (a) CO₂, (b) He, (c) N₂O laparoscopy. Baseline values were established for parietal and visceral peritoneal pH. Intraabdominal pressure was then increased stepwise at 1-mmHg intervals to 15 mmHg. After pressure was maintained for 15 min at each setting, parietal and visceral peritoneal pH were measured.Results Ambient gas environment was the major determinant of parietal peritoneal pH. Carbon dioxide caused parietal peritoneal acidosis. Helium, N₂O, and Lift caused alkalotic parietal peritoneal pH. Intraabdominal pressure had a minor effect on parietal peritoneal pH. At higher intraabdominal pressure (12–15 vs 5–8 mmHg), CO₂ caused a slight decrease in parietal peritoneal pH, whereas N₂O and He caused a slight increase in parietal peritoneal pH. Visceral peritoneal pH remained relatively unaffected during all studies.Conclusions Parietal peritoneal pH during laparoscopy was highly dependent on the ambient gas environment. The effect of intraabdominal pressure on parietal peritoneal pH was of minor significance. Carbon dioxide caused a slight worsening of parietal peritoneal acidosis at higher intraabdominal pressure, whereas, N₂O, He, and Lift did not cause parietal peritoneal acidosis.     

Hemodynamic and tissue blood flow responses to long-term pneumoperitoneum and hypercapnia in the pig

Background Increased peritoneal blood flow may influence the ability of cancer cells to adhere to and survive on the peritoneal surface during and after laparoscopic cancer surgery. Carbon dioxide (CO₂) pneumoperitoneum is associated with a marked blood flow increase in the peritoneum. However, it is not clear whether the vasodilatory effect in the peritoneum is related to a local or systemic effect of CO_2. Methods In this study, 21 pigs were exposed to pneumoperitoneum produced with either CO₂ (n = 7) or helium (He) (n = 7) insufflation at 10 mmHg for 4 h, or to two consecutive levels of hypercapnia (7 and 11 kPa) (n = 7) produced by the addition of CO₂ to the inhalational gas mixture. Tissue blood flow measurements were performed using the colored microsphere technique. Results Blood flow in peritoneal tissue increased during CO₂, but not He, pneumoperitoneum, whereas it did not change at any level of hypercapnia alone. There was no change in blood flow in most organs at the partial pressure of CO₂ (PaCO₂) level of 7 kPa. However, at a PaCO₂ of 11 kPa, blood flow was increased in the central nervous system, myocardium, and some gastrointestinal organs. The blood flow decreased markedly in all striated muscular tissues during both levels of hypercapnia. Conclusion The effect of CO₂ on peritoneal blood flow during laparoscopic surgery is a local effect, and not attributable to central hemodynamic effects of CO₂ pneumoperitoneum or high systemic levels of CO₂.     

Randomized trial of different intraabdominal pressures and acid–base balance alterations during laparoscopic cholecystectomy

BACKGROUND: Experimental and clinical studies document risks of acid-base balance alterations toward acidosis and hypercapnia during intraperitoneal carbon dioxide insufflation. The aim of this study was to assess the influence of different insufflation pressures on arterial blood gas changes and acid-base alterations during laparoscopic cholecystectomy and immediately postoperatively. METHODS: Thirty patients were randomized to receive either 10 or 15 mmHg insufflation pressure. Anesthesia was standardized for both groups. The following parameters of acid-base balance were recorded: pH, pCO2, pO2, base excess (BE), HCO3. Suitable data were analyzed by the Mann-Whitney U-test. RESULTS: Pneumoperitoneum with carbon dioxide caused a decrease in pH toward acidosis that was either respiratory or mixed in origin. There were no statistically significant differences in acid-base balance alterations between the two groups of patients. CONCLUSIONS: Carbon dioxide pneumoperitoneum causes alterations of the acid-base balance, mostly of respiratory or mixed type. Lowering of the insufflation pressure from 15 to 10 mmHg does not contribute to the elimination of acid-base balance alterations during laparoscopic cholecystectomy.     

Heating of carbon dioxide during insufflation alters the peritoneal fibrinolytic response to laparoscopic surgery

Background Laparoscopic surgery is evolving rapidly. It involves the creation of a pneumoperitoneum, mostly using carbon dioxide. Cooling of the peritoneum, due to insufflation, might traumatize the peritoneum and disturb peritoneal fibrinolysis, important in peritoneal healing processes. The current study was performed to elucidate the effects of the temperature of insufflation gas on the peritoneal fibrinolytic response to laparoscopic surgery. Methods Thirty patients scheduled for laparoscopic cholecystectomy were randomized in two groups: one group in which the pneumoperitoneum was created with carbon dioxide at room temperature, and one wherein carbon dioxide at body temperature was used. Peritoneal biopsies were taken at the start and at the end of surgery. Tissue concentrations of tPA antigen, tPA activity, uPA antigen, and PAI-1 antigen were measured using ELISA techniques. Results Peritoneal PAI-1 antigen levels were significantly higher at the end of the procedure in patients operated with carbon dioxide at room temperature (p < .05). A slight, but not significant, decrease in tPA antigen and activity was observed in both groups during the procedure. Peritoneal concentrations of uPa antigen did not change during the procedure. Conclusions The temperature of carbon dioxide used for insufflation of the abdominal cavity affects peritoneal biology. Cooling of the peritoneum by unheated carbon dioxide causes increased peritoneal PAI-1 levels, important in peritoneal healing processes.     

Intraperitoneal and retroperitoneal carbon dioxide insufflation evoke different effects on caval vein pressure gradients in humans: evidence for the starling resistor concept of abdominal venous return

BACKGROUND: The authors hypothesized that intraperitoneal and retroperitoneal carbon dioxide insufflation during surgical procedures evoke markedly different effects on the venous low-pressure system, induce different inferior caval vein pressure gradients at similar insufflation pressures, and may provide evidence for the Starling resistor concept of abdominal venous return. METHODS: Intra- and extrathoracic caval vein pressures were measured using micromanometers during carbon dioxide insufflation at six cavity pressures (baseline and 10, 15, 20, and 24 mmHg and desufflation) in 20 anesthetized patients undergoing laparoscopic (supine, n = 8) or left (n = 6) or right (n = 6) retroperitoneoscopic (prone position) surgery. Intracavital, esophageal, and gastric pressures also were assessed. Data were analyzed for insufflation pressure-dependent and group effects by one-way and two-way analysis of variance for repeated measurements, respectively, followed by the Newman-Keuls post hoc test (P < 0.05). RESULTS: Intraperitoneal, unlike retroperitoneal, insufflation markedly increased, in an insufflation pressure-dependent fashion, the inferior-to-superior caval vein pressure gradient (P < 0.00001) at the level of the diaphragm. In contrast to what was observed with retroperitoneal insufflation, transmural intrathoracic caval vein pressure increased at 10 mmHg insufflation pressure, but the increase flattened with an insufflation pressure of more than 10 mmHg, and pressure decreased with an inflation pressure of 20 mmHg (P = 0.0397). These data are consistent with a zone 2 or 3 abdominal vascular condition during intraperitoneal and a zone 3 abdominal vascular condition during retroperitoneal insufflation. CONCLUSIONS: Intraperitoneal but not retroperitoneal carbon dioxide insufflation evokes a transition of the abdominal venous compartment from a zone 3 to a zone 2 condition, presumably impairing venous return, supporting the Starling resistor concept of abdominal venous return in humans.